A broad wireless outage knocked out 911 service and some other cell phone calls in much of Oregon and Southwest Washington early Wednesday morning.

The issue began around 3:45 a.m. and was fixed at 7:20 a.m., according to Verizon Wireless spokesman Scott Charlston. He said the issue affected Sprint and Verizon customers, and possibly others. (Update, 10:40 a.m.: AT&T said it does not have any reports of an outage.)

At first, Charlston said, reports indicated only 911 service was disrupted. But it's now evident that some other calls were blocked, too.

"It was a small percentage," he said. "Under 10 percent of calls were blocked."

It's not immediately clear how widely the 911 failure affected emergency response in the region.

The outage affected customers from Klamath and Josephine counties in southern Oregon all the way to Clark and Cowlitz counties in Southwest Washington. Multnomah and Washington counties were not on Verizon's initial list of affected regions, but Charlston did not rule out customers in those areas having troubles, too.

Problems stemmed from an issue in Sprint's communications network, according to Charlston. Cell phone carriers lease space on their long-haul networks to one another to carry phone traffic after it reaches local cell phone towers.

Sprint did not immediately return calls seeking comment on the outage.

Initial reports indicated that a portion of Sprint's fiber-optic network was cut, but Charlston said that no longer appears to be the case. He said it's too soon to say just what caused the trouble.

"We're still kind of early in this investigation in terms of finding out exactly what happened," he said.